When writing stylesheets (CSS) for the web it is not recommended to hard code the colors in each stylesheet rule - because often it is a tedious task to adopt or change them afterwards.
Therefore often people use CSS preprocessors like LESS or SaaS or Stylus where you can define variables or other to ease the job.
If you already work in Pharo you might want to easily write your stylesheets in Smalltalk. Thats the idea behind "Stylesheet" - a project to define CSS like stylesheet in Pharo applications.
The project was now migrated from SmalltalkHub to GitHub and can be found on: https://github.com/pharo-contributions/Stylesheet